Seems like WU moved to different hosting or to different servers. This has caused an IP address change for their servers. Normally any weather station that was programmed to upload to a fully qualified domain address (URL) would only need to possibly be restarted or the router restarted to get new DNS IP addresses. Or wait out till DNS expires (usually less than 24 hours), and then the new IP addresses would be acquired to be able to send to the new servers.
But there are a number of possible problems...
- If the weather station is configured by the user or by the manufacturer to upload to an IP address rather than a fully qualified domain address (URL) then you have an upload problem until you or the manufacturer updates the address. What this means is that DNS is as not being used to find out IP addresses.
- In some weather stations the upload server address may be hard coded by the manufacturer. This leaves the user with no way to fix the problem, unless the manufacturer issues a firmware update. Or in the case of some manufacturers like Davis where you upload to Weatherlink.com and then they upload to WU, would be a situation where it is out of the users hands to remedy, as the upload is handled by the intermediary service.
- It is also possible that WU has dropped an old URL address that does not conform to their current Upload Protocol Documentation. For example let's suppose at some point it was possible to upload to purpledinosaur.wunderground.com and DNS would resolve this to WU servers and now WU has decided to drop purpledinosaur.wunderground.com, well then in this case your weather station would be using DNS but you would be using a URL that is no longer valid and hence you would not be able to upload. As before if you can change the URL then you can fix the problem, but if it is hard coded then you would need to depend on the manufacturer to fix the problem.
Now just because you may be in a situation where the manufacturer has hard coded the WU upload server address does not mean you can't fix the problem a different way. With most stations regardless of brand; Acurite, Ambient, or Davis (and others), you can change the way you upload to WU by using other means, like other software. Some examples of other software are; Acuparse, Cumulus, Meteobridge, WeeWx, Weather-Display. Depending on what your station is will determine compatibility with these options, but typically one or more of these will work. Using these other software provides you with more control, direct upload and often better options like rapidfire to WU.